Fig. 13From: Risk factors for adjacent segment degeneration after posterior lumbar fusion surgery in treatment for degenerative lumbar disorders: a meta-analysisa The standardized mean difference (SMD) estimate for preoperative lumbar lordosis (LL) in 2 groups. b The standardized mean difference (SMD) estimate for post-operative LL in 2 groups. CI = confidence interval, df = degrees of freedom, M-H = Mantel–HaenszelBack to article page